Probably depends on a number if factors, like how thick each of your coats are. If you are using a rattle can then the coats are probably on the thickish side. I always find I can lay much thinner, but well covered coats with my airbrush, compared to the cans. If you are concerned about the detail you could always try rescribing it, but then you'd be down to the plastic again.
I wouldn't sweat it too much, go ahead and patch it like you suggested, it will probably work. If it doesn't then put it down to experience. Learn from it so your next paintjob will be closer to the perfection we all seek, but rarely achieve.
